We should port https://github.com/cyphar/filepath-securejoin/pull/35 to libpathrs so that we don't regress https://github.com/opencontainers/runc/issues/4543.
We should port cyphar/filepath-securejoin#35 to libpathrs so that we don't regress opencontainers/runc#4543.